Polymerization of ethylene with a catalyst of alkylaluminum and a v-a metal salt



United States Patent PGLYMERIZATION OF ETHYLENE WITH A CATA- LYST OF ALKYLALUMINUM AND A V-A METAL SALT Edwin J. Vandenberg, Wilmington, DeL, assignor to Hercules Powder Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application March 19, 1957 Serial No. 646,960

Claims. (Cl. 260--94.9)

This invention relates to the polymerization of ethylene under relatively mild conditions of pressure and temperature, and more particularly toa new catalyst for the polymerization of ethylene under such conditions.

K. Ziegler has described the polymerization of ethylene with organometallic compounds of the metals of group III-A of the periodic table, i.e., organometallic compounds of aluminum, gallium and indium to produce polymers varying in molecular weight from dimers up to the wax range polymers. He has also described the preparation of high molecular weight crystalline polymers by contacting ethylene with a mixture of an organoaluminum compound and a compound of a metal group IVB, V-B, VI-B or VIII of the periodic table.

Very surprisingly, it has now been discovered that ethylene may be polymerized with a catalyst formed by mixing an organometallic compound of a metal of groups I-A, II-A or IIIA of the periodic table with a salt of a group V-A metal, i.e., an arsenic, antimony or hismuth salt. It was entirely unexpected that an organometallic compound of a metal of one of the main groups of the periodic table could react with a salt of a metal of another main group of the periodic table to produce a catalyst that was eflective for the polymerization of ethylene under mild conditions of temperature and,

pressure.

The polymerization of ethylene in accordance with this invention may be carried out in a wide variety of ways. It may be carried out as a batch or continuous operation and generally is carried out in the presence of an inert organic diluent as the reaction medium. Any inert liquid organic solvent may be used, as for example, aliphatic hydrocarbons such as hexane, heptane, etc., cycloaliphatic hydrocarbons such as cyclohexane, aromatic hydrocarbons such as benzene, toluene, xylene, etc., or any mixture of such hydrocarbons, halogenated hydrocarbons such as methylene chloride, ethylene chloride, chloroform, carbon tetrachloride, chlorobenzene, etc.

The polymerization of ethylene in accordance with this invention may be carried out by forming the catalyst in situ, i.e., adding first one catalyst component followed by the other, or adding the two catalyst components simultaneously to the ethylene, or a preformed catalyst "ice monoussulfate, arsenic bromide, arsenous chloride, arsenous oxychloride, arsenic pentachloride, bismuth acetate, bismuth chloride, bismuth bromide, bismuth dichloride, bismuth oxychloride, bismuth phosphate, bismuth sulfate, etc. Of particular value are the halides of these metals. It is usually desirable to use these metal salts in the form of a solution or suspension in a diluent, as for example, a diluent of the type used in the polymerization process or to use them in a finely divided form such as is obtained by grinding by any desired means, as for example, in a pebble mill, ball mill, etc.

may be used by mixing the group V-A metal salt with the organometallic compound, usually in an inert organic diluent, and then adding the ethylene to the preformed catalyst. Obviously, many other variations in the process may be made, for example, either one or both components of the catalyst may be added in increments during the polymerization.

Any salt of the group V-A metal, i.e., arsenic, antimony or bismuth, may be used as one of the catalyst components in accordance with this invention. The salt may be an inorganic or organic salt, etc. Exemplary of the antimony, arsenic and bismuth salts that may be used are antimony trichloride, antimony pentachloride, antimony tribromide, antimony pentachloride bromide, antimonous oxychloride, antimonic oxychloride, anti- The organometallic compound that is reacted with the group V-A metal salt may be any organo compound of an alkali metal, alkaline earth metal, or earth metal. Particularly efiective are the organoaluminum compounds such as the alkylaluminum compounds. Exemplary of the organometallic compounds that may be used are alkali metal alkyls or aryls such as butyllithium, amylsodiurn, phenylsodium, etc., dimethylmagnesium, diethylmagnesium, diphenylmagnesium, butylmagnesiumchloride, phenylmagnesium bromide, and aluminum compounds such as trimethylaluminum, triethylaluminum, tripropylaluminum, triisobutylaluminum, trioctylaluminum, tridodecylaluminum, dimethylaluminum chloride, diethylaluminum bromide, diethylaluminum chloride, ethylaluminum dichloride, the equimolar mixture of the latter two known as aluminum sesquichloride, dipropylaluminum fluoride, diisobutylaluminum fluoride, diethylaluminum hydride, ethylaluminum'dihydride, diisobutylaluminum hydride, etc., and complexes of such organoaluminum compounds, as for example, sodium aluminum tetraethyl, lithium aluminum tetraoctyl, etc., aluminum hydride, and complexes of aluminum hydride such as lithium aluminum hydride. As in the case of the group V-A metal salt, if the organometallic compound is not at least partially soluble in the diluent used for the polymerization process, it may be desirable to ball-mill or otherwise finely divide the compound prior to its use in the process.

When the group V-A metal salt and the organometallic compound are mixed in the preparation of the catalyst, a reaction takes place, the nature of which is not completely understood. Nevertheless, the catalyst so produced is extremely eflective for the polymerization of ethylene. The molar ratio of the group V-A metal salt to the organometallic compound may be varied over a wide range and will depend on the type of organometallic compound that is mixed with the particular group V-A metal compound. In general, the molar ratio of the organometallic-compound to the group V+A metal compound-will be from about 0.1:1 to :1 and more usually'will be from about 0.3:1 to 10:1.

The selection of the temperature and pressure used for the polymerization process will obviously depend upon the activity of the catalyst system being used, the degree of polymerization desired, etc. In general, the polymerization will be carried out at room temperature or slightly above, but any temperature within the range of from about -50 C. to about 150 C., preferably from about 20 C. to about C. and more preferably from about 20 C. to about 100 C. may be used. In the same way, while atmospheric pressure or a pressure of only a few pounds may be used, the polymerization may be carried out over a wide range of pressures, but higher pressures do not appreciably alter the course of the polymerization and, hence, are not required.

As will be obvious from the following examples, many variations may be made in the process of this invention. For example, in many instances, it may be desirable to add a viscosity-reducing agent such as hydrogen, etc., to reduce the viscosity of the polymer that is obtained. In some cases, oxygen may function as an activator or other desirable function and may be added.

The following examples will demonstrate the process of polymerizing ethylene in accordance with this invention and some of the many modifications that can be made in this process. The molecular weight of the poly- As may be seen from the foregoing examples, the process of this invention makes it possible to polymerize ethylene and produce polyethylenes of high or low molecular weight and of varying degrees of solubility mers produced in these examples is indicated by the re- 5 as desired. duced specific viscosity (RSV) given. By the term The periodic able referred to in the specification and reduced specific viscosity is meant the 7 Sp/C deterclaims is that set forth in the Handbook of Chemistry mined on an 0.1% solution of the polymer in decalin, and Physics, published by the Chemical Rubber Publishcontaining 0.1 g. of the polymer per 100 ml. of soluing Company, pages 392-393 of the 36th edition. tion (unless otherwise indicated), at 135 C. All parts 10 What I claim and desire to protect by Letters Patent and percentages are by weight unless otherwise indicated. is:

1. The process of polymerizing ethylene which com- EXAMPLES prises contacting ethylene with a catalyst formed by mixing an alkylaluminum compound with a salt of a metal of group VA of the periodic table, and recov- In each of these examples polymerization vessels, ering a polymer f h 1 freed from air, were charged with the diluent (about 35 2 Th process of l i 1 h i h group V A parts of n-heptane in Examples 1, 3 and 4 and about 40 metal l i an antimony m Parts of toluene in Example and 2 Parts of 33560113 3. The process of claim 1 wherein the group VA ethylene. The initial pressure in each case was about metal l i bi h Salt, 50 P- The alkylaluminum Compound dissolved in 4. The process of claim 2 wherein the antimony salt n-heptane was added and after equilibrating at 30 C., i antimony i hl id the group VA metal salt was then added. The bismuth 5 Th process f l i 2 h i th ti l trichloride used in Example 1 was ball-milled in n-hepi antimony h1 id m nd in Example 2 w gr n wi h gl ss beads in 6. The process of claim 3 wherein the bismuth salt a glass container to a particle size of 1-3 microns in i bis uth r i hl rid n-heptane. The antimony trichloride used in Example 7. The process of polymerizing ethylene which 3 was ball-milled in n-heptane whereas the antimony prises contacting ethylene with a catalyst formed by mixpentachloride used in Example 4 was added as a 1 M ing antimony trichloride with ethylaluminum dichloride, solution in carbon tetrachloride. The group VA metal and recovering a polymer of ethylene. salt, the aluminum compound, and the amount of each 8. The process of polymerizing ethylene which comexpressed as millimoles per liter, and the reaction time prises contacting ethylene with a catalyst formed by mixare set forth in the following table. After the indicated ing antimony pentachloride with ethylaluminum dichlornumber of hours at 30 C., the polymerization was ide, and recoveringapolymer of ethylene. stopped by adding 4 parts of ethanol. The insoluble 9. The process of polymerizing ethylene which compolymer that had separated was then isolated by filtraprises contacting ethylene with a catalyst formed by tion, refluxed with a 10% solution of hydrogen chloride mixing bismuth trichloride with triethylaluminum, and in methanol, washed with methanol until neutral, and recovering apolymer of ethylene. then dried. The RSVs of some of the polyethylenes so 10. The process of polymerizing ethylene which comobtained are. set forth in the table. (The polyethylenes prises contacting ethylene with a catalyst formed by mixproduced in Examples 3 and 4 Were too insoluble in deing an alkylaluminum compound with a metal salt secalin to measure.) The polyethylenes obtained in Exlected from the group consisting of bismuth trichloride, amples 1 and 2 were crystalline as shown by their X-ray antimony trichloride and antimony pentachloride, and diffraction pattern. recovering a polymer of ethylene.

Table Group VA Alkylaluminum Reaction Example Metal Salt mmole/l Compound mmole/l. Diluent 'lgrlnse, RSV

20 AI(C2H5)3 4O n-heptane. 19 2O Al(CzH5) Cl (lo 19 20 Al(C2H5)C12 o 2D Al(G2H5)s. toluene.- 20 Al(C2H5)2 20 Al(C2H5)C12 2O A1(C2H5)ac 20 Al(C2H5)zCl 20 aucmoolz g8 AI(C2H5)3 20 Imoznaon 1 Measured as an 0.05% solution in deealin.

References Cited in the file of this patent UNITED STATES PATENTS 2,085,535 Langedijk et a1. June 29, 1937 2,406,869 Upham Sept. 3, 1946 2,827,445 Bartolomeo et al Mar. 18, 1958 FOREIGN PATENTS 540,459 Belgium Aug. 31, 1955 716,159 France Dec. 16, 1931 

1. THE PROCESS OF POLYMERIZING ETHYLENE WHICH COMPRISES CONTACTING ETHYLENE WITH A CATALYST FORMED BY MIXING AN ALKYLALUMINUM COMPOUND WITH A SALT OF A METAL OF GROUP V-A OF THE PERIODIC TABLE, AND RECOVERING A POLYMER OF ETHYLENE. 